docs: def _create_command_file(self, expect, send):
  		"""Internal function. Do not use.
  
  		Takes a long command, and puts it in an executable file ready to run. Returns the filename.
  		"""
  		shutit = self.shutit
  		random_id = shutit_util.random_id()
  		fname = shutit_global.shutit_global_object.shutit_state_dir + '/tmp_' + random_id
  		working_str = send
  		# truncate -s must be used as --size is not supported everywhere (eg busybox)
  		assert not self.sendline(ShutItSendSpec(self,
  		                                        send=' truncate -s 0 '+ fname,
  		                                        ignore_background=True)), shutit_util.print_debug()
  		self.expect(expect)
  		size = shutit_global.shutit_global_object.line_limit
  		while working_str:
  			curr_str = working_str[:size]
  			working_str = working_str[size:]
  			assert not self.sendline(ShutItSendSpec(self,
  			                                        send=' ' + shutit.get_command('head') + ''' -c -1 >> ''' + fname + """ << 'END_""" + random_id + """'\n""" + curr_str + """\nEND_""" + random_id,
  		                                            ignore_background=True)), shutit_util.print_debug()
  			self.expect(expect)
  		assert not self.sendline(ShutItSendSpec(self,
  		                                        send=' chmod +x ' + fname,
  		                                        ignore_background=True)), shutit_util.print_debug()
  		self.expect(expect)
  		return fname